title: Ultraselective and sensitive detection of xylene and toluene for monitoring indoor air pollution using Cr-doped NiO hierarchical nanostructures.
abstract: Ultraselective and sensitive detection of xylene and toluene with minimum interferences of other indoor air pollutants such as benzene, ethanol, and formaldehyde is achieved using NiO hierarchical nanostructures doped with Cr. Pure and 1.15-2.56 at% Cr-doped NiO flower-like hierarchical nanostructures assembled from nanosheets are prepared by a simple solvothermal reaction and their gas sensing characteristics toward o-xylene and toluene gases are investigated. The 1.15 at% Cr-doped NiO hierarchical nanostructures show high responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 11.61 and 7.81, respectively) and negligible cross-responses to 5 ppm of benzene, formaldehyde, ethanol, hydrogen, and carbon monoxide. However, pure NiO nanostructures show low responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 2.01 and 1.14, respectively) and no selectivity toward any specific gas is observed. Significant enhancement of the response and selectivity to o-xylene and toluene is attributed to the decrease in the hole concentration in NiO and the catalytic oxidation of methyl groups by Cr doping.
authors.affiliation: Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, Republic of Korea.
authors.forename: Hyo-Joong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Ji-Wook
authors.initials: JW
authors.lastname: Yoon
authors.forename: Kwon-Il
authors.initials: KI
authors.lastname: Choi
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Jang
authors.forename: Ahmad
authors.initials: A
authors.lastname: Umar
authors.forename: Jong-Heun
authors.initials: JH
authors.lastname: Lee
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D002857:Chromium / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D049329:Nanostructures / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D012680:Sensitivity and Specificity; D014050:Toluene / Q000032:analysis*; D014992:Xylenes / Q000032:analysis*
chemical_list: D014992:Xylenes; D002857:Chromium; D014050:Toluene; D009532:Nickel; C028007:nickel monoxide